Bimetallic hygrometer



Dec. 9, 1941. w. F ALDER v 2,265,767

BIMETALLIC HYGROMETER Filed April 27, 1958 3 Sheets-Sheet l 9, 1941. w. F. ALDER BIMETALLIC lHYGrROMETER Filed April 27, 1938 3 Sheets-Sheerl 2 Dec. 9, 1941. w. F. ALDI-:R 2,265,767

BIMETALLIC HYGROMETER Filed April 27, 1938 3 Sheets-Sheet 3 illll Patented Dec. 9, 1941 UNITED STATES PATENT OFFICE BIMETALLIC HYGROMETER William F. Alder, Altadena, Calif., assigner to Frank E. Wood, Monrovia, Calif., as trustee Application April 27, 1938, Serial No. 204,600

(Cl. 20G-52) 10 Claims.

I designate my invention as a bi-metallic hygrometer in that I actuate the indicating elements of the instrument by the thermal expansion and contraction of bi-metallic strips or the equivalent. Such elements co-relate the changes of temperature somewhat equivalent to hygrometric determinations by a so-Called wet and dry bulb method. This invention may be considered as a simplification and a less expensive instrument than that described in my patent application for Electric hygrometer, Serial No. 110,131, filed November l0, 1936, Patent No. 2,- 177,630, issued October 31, 1939. My present invention utilizes a hygrometric chart mounted on a drum or forming part of a cylinder, this chart being provided with numerals or other insignia showing the relative humidity for different air' temperatures. In conjunction with the chartl provide a pointer which may be moved over the chart, the pointer registering with the numerals and indicating the relative humidity at any definite temperature at any one time. As to these features this present application resembles my patent application above identified.

An object and feature of the present invention is to move the chart, that is, rotate this on its axis by the use of bi-metallic thermo-metric elements which on account of the unequal expansion develop a torque and thus rotate the shaft and hence t-he chart. Also another object of this invention is to move the pointer by rotating its pivot through the medium of bi-metallic expansive and contractive strips in which lcase it is preferable to operate the pointer through a gear system to obtain an increased arcuate angular movement of the pointer in reference to the angular movement developed by a pivot shaft connected to the second bi-metallic strips. It is believed obvious that either the first or the second set of strips may operate in accordance with L the so-called wet bulb component of a hygrometric instrument in which the changes of temperature are governed in part by the evaporation of water.

A more detailed object and feature of my invention includes a mounting for the first bimetallic elements for rotating the drum and chart and these being influenced solely by air temperatures irrespective of the humidity and in which case a registering or zero setting device is employed, this involving a movable support such as a pin on a setting disk, the other end of the coiled bi-metallic strips are directly connected to the shaft of the drum and therefore rotate the drum through various angular turns in accordance with changes of temperature either upwardly or downwardly considered in relation to the zero setting. A detailed feature of my invention in relation to the humidity regulation includes a mounting' of the second set of bimetallic strips with an adjustable support for the free ends, this bein'g governed by micrometer adjustmentscrews. The opposite end preferably at the center of a spiral`coil is connected to a rocking shaft. T he coils of the second set are maintained in a moist condition by a wick eX- tending into a reservoir of water so that the expansion and contraction of the coils of the second unit is regulated by the changes of temperature in conjunction with the evaporation of water from the exposed wick. A further detail feature in the humidity controlled unit consists of the employment of meshing segmental gears, one connected to the rock shaft and the other to a pivot shaft for the pointer so that an increased or magnified movement of the pointer is obtained.

Another object and feature of my invention is in the employment of the instrument to control the operation of secondary instruments in accordance with the changes of relative humidity and for such purpose I have an electrical control of for instance relays or the like in which conducting strips are mounted on the chart aligned with numerals showing substantially constant humidity through a temperature scale. The pointer is then provided with an electrical contact element which may engage the conductor or conductors and thus initiate the.closing and opening of a first electric circuit which circuit may be utilized to operate one or more relays and thus control the operation of various air humidifying machines or the like. In this present construction I preferably arrange the strip conduc- .tors spaced apart on the chart to include between the strips satisfactory ranges of humidity change which do not require the actuation of the humidity control machines. However should the humidity become too high the pointer will contact one conductor and establish a first operative circuit and should the humidity fall too low, the pointer will contact a second conductor and establish a second control circuit.

My invention is illustrated in connection with the accompanying drawings, in which:

Fig. 1 is an elevational section taken on the section line I-I of Fig. 2 in the direction of the arrows, thus showing the interior of the instrument in elevation, the front portion of the cover being removed.

Fig. 2 is a vertical section taken substantially on the line 2-2 of Fig. l in the direction of the arrows.

Fig. 3 is a. detail vertical section on the linel 3-3 of Fig.'2 in the direction of the arrows through the chart drum, certain of the interior parts "being shown in elevation.

Fig. 4 is adetail vertical section on the line 4 4 of Fig. 1 in the direction of'the arrows.

Fig. 5 is a detail vertical section on the line 5-5 of Fig. 2 in the direction of the arrows.

Fig. 6 is a schematic drawing of the mechanical equipment together with an electrical wiring diagram.

Referring rst to the mechanical features depicted in Figs. 1 through 5, a wall plate il is indicated as the main supporting structure for the equipment, however it will be understood that any suitable type of supporting base may be utilized. To this wall plate which is preferably made of metal, I attach a frame I2. Such frame has vertical sides i3 and i3', a bottom plate M and a top l5. In this frame I construct a reservoir designated 20 which includes a Iback plate 2|, a front plate 22, the reservoir bottom 23, there being a filling neck 2li, this having a closure cap 25 provided with a head 2S and a sleeve 2l. In the front plate there is an opening 28 adjacent the top. This front plate which forms a panel for supporting other parts of the instrument extends to the opposite sides i3 and i3 of the frame. The frame assembly with the reservoir is attached tothe wall 'plate by the medium of lugs 29 and attaching screws 30. The side i3 has a molded recess 3| extending from front to back and connecting with a horizontal back recess 32 from which there is a vertical recess 33 molded in the back 2| of the reservoir. These recesses are to accommodate electric wires. An enclosing cover 00 has a bottom 0|, two opposite sides 02 and 03. The cover has a top lili with an opening i5 to accommodate the filling neck 20. The front panel d6 of the cover is provided with a glass window il adjacent its lower portion and with a screen 48 tted in an upper window. This screen provides for air circulation. The cover is attached to the frame structure l2 by screws i9 or the like on the sides. Such cover may be readily removed to inspect and adjustl the equipment.

The humidity responsive assembly designated S0 employs a boss 6| on the front plate 22. A plate 63 is mounted on this boss being preferably spaced therefrom by a heat insulating strip 03'. By means of a series of screws or studs 60 with spacers. a front plate 65 is attached to the rear plate 83. The front plate has openings 60 through which the set screws 61 may be reached to attach this assembled frame to the boss 6|.

A rock shaft 10 is journalled in the plates S3 and 65 to which shaft is connected a bimetallic thermal coil 1|. This coil is in the form of a spiral and has its inner end 'l2 attached to the rock shaft. The free outer end 13 is bent outwardly, note particularly Fig.i5. and has an eye 14 formed in the end. This eye ts over a pin 15 mounted on the stud 76, the stud having a projection 11. A complementary stud 18 has a socket i9 in which the pin 15 ts. Such studs 18 also has a projecting end 00. By means of these projecting ends the studs are mounted in micrometer screws 8| and 82, each of which has a socket 83 and the screws are threaded through bosses 84 extending outwardly from the front plate y 22. By this means the tension of the coil may be adjusted to position the rock shaft as desired so that a pointer, hereinafter described, may be adjusted to occupy the correct position in accordance with the humidity test when the instrument is set up.

'I'he coil 'El of the bimetallic thermnstatic strip is covered with a wick 90, which wick has a portion 9| extending through the opening 20 in the upper part of the reservoir wall. A depending end 92 dips into the water in the reservoir. The exposed part of the wick is thus always maintained dampV by the capillary action of the water owing in the wick and is evaporated from this wick. It will be noted that the wick is directly exposed inside of the screen i8 and is thus subjected to the air of a room or the like and thus responsive to the temperature and humidity action.

The humidity-indicating mechanism designated by the numeral |00 includes a segmental gear i0 lv attached to the rock shaft 70. This gear meshes with a complementary segmental gear |02 which has its shaft |03 journaled in the plates 63 and S5. A pointer |00 is connected to the shaft |03, or for simplicitys sake, connected to an extension of the segmental gear |02. The lower end |05 on the pointer is visible through the window lil.

The temperature humidity chart assembly H0, note particularly Figs. l, 2, and 3, employs a cylinder or drum on the periphery of which is mounted a chart l2. This chart has temperature indicia and a scale of the relative humidities substantially the same as in my Patent No. 2,177,630, above identified. At Athe margins ||3 are columns giving the temperatures. The humidity readings ||ll are arranged in curved or arched lines. The pointer arm |00 has a contact point H5 with a spring coil i I6 and connected by a ne wire Hl. The curvature of the humidity readings for Vthe same temperatures are made on an arc corresponding to the swing of the pin end i l5 as it would move across the chart in accordance with different humidity conditions.

'Ihpv drum or chart may be mounted in any suitable manner. However, this is illustrated as having a head |20` note particularly Fig. 3, this head having an opening 2| with a close fit on the drum shaft |22. At the opposite end there is a second head i123 fastened by a set screw |24 or the liketo the shaft. The shaft has its opposite ends of reduced diameter as at |25. At one end this ts in a journal 826 in the vertical side i3 of the frame 2. The opposite end is journaled in a rotatable bearing sleeve |27 mounted for rotation in the other wall |3 of the frame and on this iournal there is an adjusting disc S28 preferably having a knurled periphery and positioned adjacent the head |23 to allow a iinger engagement with this knurled disc.

The linear temperature thermostats |30 include one or more bimetallic spiral coils 3| the outer end |32 of which is secured to a pin |33 such pin projecting from the disc |28 and parallel to the shaft |22. Thecenter convolution |34 is secured to the shaft |22. Therefore, the disc |28 Vmay be rotated-so that the temperatures on the chart fall in the correct position when a test is made in setting up the instrument. This disc |28 has a friction mounting preventing its accidental turning, therefore, as the outer ends of the thermostatic coils are held in a lxed position any expansion or contraction due to changes in air temperature causes rotation of the shaft |22 and hence of the drum m with the chart.

This gives an indication of the changes ottemperature independent ofthe humidity.

Il' the device is merely to be used as an indicator of relative humidities at different temperatures when the instrument is properly set up and calibrated, the pointer tip will register with a humidity-identifying numeral for the partiular air temperature obtained by the action of the temperature thermostat assembly |30. Thenpresuming the humidity should change while the temperature remained constant, the pointer IM will swing in an arc and indicate different humidities; action of changes in temperature accompanied by changes in humidity which will be indicated by the conjoined action of the pointer tip on the chart o f the drum.

Where I desire to give an electric signal of the humidity at particular temperatures or to operate various machines to regulate or control humidity, I may incorporate electrical equipment for instance as shown in the diagram of Fig. 6. In this illustration a power supply line |50 is illustrated as having leads |5| and |52. If these have an alternating current supply a rectifier |53 is included. One of the leads |54 has a brush |55 contacting a curved or circular contact elel ment |56 connected by a lead wire |51 to the end or pointer wire H5. This lead extends along the pointer arm |04. A rst pair of conductor wires l 58 and |69 are attached to the drum and extend across the chart in a diagonal manner, each wire being of such coniiguration thatit registers with numerals indicating substantially the same humidity. For this construction it is preferable that the drum be made of insulating material, the wires being secured to the drum'by having inwardly turned ends |60 secured to the drum. Ii' desired a second set of wires |6| and |62 may be located on the drum for a different set of humidity values. Each pair of wires thus define a humidity range, one wire for instance may deiine the maximum allowable humidity valuesl and the other wire of the pair, the other humidity value. Each of the pair of Wires |58, |59, |60, |6| and |62 are connected to leads |63 There also may be the combination metallic response of the pointer arm to the v f curate control of the humidity in a room or the and |64 which may be mounted on the inside of One of these brushes, for instance the brush |61,'has a lead |10 to an electro-magnet |1| having the winding |12, the return being by the connection |13 to the power line |5|. The oppo- 'site brush |68 is illustrated as having a connecting lead |15 to a second electro-magnet |16, this having the Winding |11 with a return lead |18 to the return wire |5|, thus in accordance with the position of the pointer arm |04 and its pin end ||5, a contact may be made for instance withconductor |58 or conductor |59 and thus energize either the electro-magnet |1| or the other electromagnet |16.

These magnets form part of a relay, both being illustrated as similar and designated |80 including an armature switch |8| having the make and break contacts |82, connections |83 through a b e seen that my equipment 1with the mechanical openation of the bi-metallic temperature responsive movement of the chart. and also the bilike where the instrument is installed may be obtained. It is manifest that if desired the conducting Wires may be inserted or mounted on a drum or the equivalent, omitting the chart as in some cases it is desired to have the humidity control Without persons observing the humidity indication. By having a plurality of sets of conductors mounted on the drum or over the chart, it will be seen that the same drum and other equipment may be utilized for an entirely difierent humidity range control.

In certain of the claims I have designated the thermometric elements responsive to temperature and humidity as mechanical in contradistinction to those which may be electrical or partly electrical such as in my patent above identified.

Various changes may be made in the details of the construction without departing from the spirit or scope of the invention as deiined by the appended claims.

I claim:

1. In a device as described, the combination of a pivotally mounted gear segment, a mechanical thermometric element in the form of a spiral coil having one end connected to said segment, a micrometer adjustment for the opposite end, a wick with means to dampen said wick associated with said element to influence the action of said element in relation tothe air humidity, a second segmental gear meshing with the first gear and pivotally mounted, a pointer arm extending from the second gear and having a pointer means on the end thereof.

2. In a device as described and claimed in claim 1, a rotatable shaft, a cylindrical means with a chart mounted thereon, the chart having indicia of temperatures and relative humidities, a second thermometric element in the form of a spiral with one end connected to the shaft, a setting disk rotatably Amounted on the axis of the shaft, a pin extending therefrom"and the outer end of the second thermo-metric spiral element being connected to the pin, the chart andthe pointer end being relatively positioned for the pointer end to move over the chart and thus with the rotation of the shaft and the chart designate various humidity values for diierent temperatures.

3. In a device as described, the combination of a housing and cover structure with a Water reservoir mounted'therein, a face plate structure 1ocated on 'the front of the reservoir, a iirst thermo-metric element including a spiral bi-metallic coil, a pivoted gear segment connected to one end of the coil, a micrometer screw adjustment for the opposite end of the coil, a second segmental gear having a pivotal mounting von the plate and meshing with the first gear, a pointer arm extending from the second gear and having a pointer end, a wick extending into the reservoir and connected with the bi-metallic coil to maintain said coil moist and a movable chart with means for operating same in relation to changes mounted on the axis of the chart and having a A setting pin thereon, a second bi-metallic thermometric element having one end connected to the l setting pin, said element being woundv in a spiral coil and having its opposite end connected to the said shaft whereby the expansion and contraction of the second thermo-metric element rotates the shaft and hence the chart.

5. In a device as described, the combination of a first mechanical thermometric element responsive to changes of air humidity in conjunction with changes of air temperature, a pivotally mounted pointer arm with a pointer end operatively connected to said element whereby the pointer is moved with its pointer end describing an arc, a rotatable shaft, a cylindrical means with a chart mounted thereon, the chart having indicia of temperatures and relative humidities, a second mechanical thermometric element in the form of a spiral with one end connected to the shaft, a setting disk rotatably mounted on the axis of the shaft, a pin extending therefrom and the outer end of the second thermometric spiral element being connected to the pin, the chart and the pointer end being relatively positioned for the pointer end to move over the chart and thus with the rotation of the shaft and the chart designate various humidity values for diierent temperatures.

6. In a device as described, the combination of a rst and a second mechanical thermo-metric element each responsive to expansion and contraction by changing temperatures, means to inuence one' of said elements b'y the evaporation of moisture in conjunction with the surrounding temperature, the other element being inuenced solely by the changes of the surrounding temperature, a rst indicator means including a pointer, a second indicator means including a bodily movable chart-like device with means indicating sub- 4 stantially constant humidity values for changing temperatures, means to actuate the pointer by one of the thermo-metric elements, means to actuate the chart by the other element, the pointer and the chart being adapted to register and thus give an indication of the humidity values through various ranges of temperatures, the chart having one or more electrical conductors mounted thereon, each conductor being positioned to register with constant humidity values through a range of temperatures, a contact element on the pointer and means to establish an electric circuit through the pointer and either of the conductors when the pointer contacts therewith.

7. In a device as described, the combination of a movable frame having an indicator chart thereon showing substantially constant humidity values for various changes of temperature, a pivoted pointer having a pointer end positioned to register with the chart, a first mechanical thermo-metric element expanding and contracting in accordance with changes of air temperature, a second mechanical thermo-metric element having a water moistened absorbent wick and exthe movable frame and the other element and i the pointer whereby during changes of air temperature and air humidity the movement of the frame with the chart and the pointer being adapted to register and thus designate the specific humidity at a specific temperature, the indicator chart having an electrical conductor mounted on the chart shaped to conform to constant humidity values through a range of temperature, the pointer having an electrical connection and a contact end to engage the said conductor when registering therewith.

8. In a device as described, the combination of a housing and cover structure with a iixed plate structure, a rst mechanical thermo-metric element including a spiral bi-metallic coil, a pivoted gear segment connected to one end of the coil, a second segmental gear having a pivoted mounting on the plate and meshing with the rst gear, a. pointer arm extending from the second gear and having a pointer end, a wick with a dampening means connected with the bi-metallic coil to maintain the coil moist, a movable chart, the pointer end of the pointer and the chart being positioned for the pointer end to move over the chart, the chart and means to operate same including a shaft rotatably mounted in the cover structure and located at right angles to the pivots4 of the segmental gears, a cylinder connected to the shaft and having the chart mounted thereon, such chart having indicia for temperatures and relative humidities, a setting disk rotatably mounted on the axis of the chart and having a setting pin thereon, a second bi-metallic thermometric eelment having one end connected to the setting pin, said element being wound in a spiral coil and having its opposite end connected to the said shaft whereby the expansion and contraction of the second thermo-metric element rotates the shaft and hence the chart.

9. In a device as described the combination of a first and a second thermo-metric element responsive to changes of temperature, means to influence one of the elements by the relative humidity of the air, the other being influenced only by changes of air temperature, a movable assembly including a iirst movable indicating element and a second bodily'movable indicating means to designate a range of changing relative humidity values for a series of constant temperatures and changing temperatures for a series of constant relative humidity values, means to actuate one of the indicators by one of the elements and the other indicator by the other element, said indicators being adapted to co-register and indicate relative humidity values for different' temperatures, a second indicating means having one or more electrical conductors positioned for each conductor to represent a certain constant relative humidity value for varying temperatures and means to close an electric circuit when the two indicator means register with a conductor.

l0. In a device as described, the combination of a first mechanical thermometric element with an absorbent wick and means to moisten said wick to.develop a response to the relative humidity changes of varying temperatures, a pivoted arm forming a pointer operatively connected to said i'lrst thermometric element to move in an arc at right angles to its pivot, a second mechanhaving designations of temperature and relative humiditythereon, means' interconnecting the second thermometric element and the charttomove the chart in relation to the pointer whereby the i pointer end moves over the chart giving an indication of temperatures andv relative humidities at such temperatures, the chart having a pair of substantially parallel conductors mounted thereon. each positioned to indicate a different set of constant humidity values for diierent-tem- 10 WILLIAM F. AIDER. 

